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Will the Chevy Volt Succeed?

544 messages,  Last post on Oct 28, 2009 at 1:11 PM

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What is this discussion about? Chevrolet Volt, Automotive News, Hybrid Cars, Coupe, Hatchback, Truck, Sedan, SUV


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#402 of 544
Re: 50 MPG Possible after battery depletion? [eaton53] by coldcranker
Sep 28, 2008 (3:08 pm)
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Replying to: eaton53 (Sep 28, 2008 10:13 am)

"Well, GM is saying 50mpg... we can try to analyze it, but we don't really know how it works, so any analysis is pure speculation. "
 
You can bet an 80% efficient transmission on the Volt (generator-to-motor path) will not get as good gas mileage as a current Corolla with an automatic transmission (31 MPG combined city/hiway) unless the battery is used in burst mode to fill in transient torque demands on the engine. The only details left are what logic thresholds GM will choose and how high they can get the MPG to.
 
Many of us were predicting that the Volt's engine would not recharge the batteries to full after battery depletion because it is a ridiculously low 50% efficient to do so. When GM announced it recently some of us were not surprised.
#403 of 544
Re: 50 MPG Possible after battery depletion? [coldcranker] by eaton53
Sep 28, 2008 (6:22 pm)
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Replying to: coldcranker (Sep 28, 2008 3:08 pm)

Frankly, the people who were predicting full recharge were foolish, since the goal has clearly been to use grid power as much as possible.
 
And they've already said 50mpg, so the battery must be assisting during peak loads and recieving a small charge from the engine and braking to maintain a minimum charge state.
 
I also expect the Volt's engine to run in far more efficient rpm ranges than a Corolla or any other conventional car including the Prius.
#404 of 544
Re: 50 MPG Possible after battery depletion? [coldcranker] by tpe
Sep 29, 2008 (5:41 am)
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Replying to: coldcranker (Sep 28, 2008 3:08 pm)

I'm not sure why you would use the Corolla as an example. Why not the Prius?
 
GM has stated many times they expect the Volt to get 50 mpg after the battery has been depleted. I've got to believe their engineers know a few things about transmission efficiency. While 50 mpg may end up being a little optimistic, especially with the new EPA ratings, it's hard to imagine that GM could be as far off as you are suggesting. Again, it's speculation on both our parts but if there was a way to bet on whether this car will get over 30 mpg with the ICE I'd definitely take that bet.
#405 of 544
Re: please dont drive on highway 40 miles [peralta] by peralta
Oct 01, 2008 (6:33 pm)
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Replying to: peralta (Sep 25, 2008 7:29 am)

This thing looks very very close to what I just proposed about an ICE with direct mechanical drive and about travel distance logic algorithm with the help of navigation system.
 
http://www.motortrend.com/features/auto_news/2008/112_0809_2011_vw_golf_twin_dri- - - ve_preview/index.html
 
http://blog.wired.com/cars/2008/10/twin-drive-is-g.html
#406 of 544
Re: please dont drive on highway 40 miles [peralta] by reddroverr
Oct 01, 2008 (8:21 pm)
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Replying to: peralta (Oct 01, 2008 6:33 pm)

huh. 12 v 16 kwh for the Volt. I didn't see an mpg mentioned. All things being equal, they are going to have to hit better than 80. Adds a tad bit of complexity for the owner. Must plug in and gas up...and since the engine works daily, you will have to have more maintenance. I wonder how big the tank will be? For the volt many could go without gas except on longer trips. I figure gas going bad might be a problem for some. I like diesels but it is a little harder to find a station as well.
#407 of 544
by stephen987
Oct 02, 2008 (3:19 am)
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Must plug in and gas up...and since the engine works daily, you will have to have more maintenance.
 
Huh? More maintenance than what? Doesn't your current car's engine "work daily"?
#408 of 544
Re: [stephen987] by eaton53
Oct 02, 2008 (3:29 am)
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Replying to: stephen987 (Oct 02, 2008 3:19 am)

Yeah, he lost me there. This will probably be the most maintenance free mainstream car yet... most people will do the work based on time, not mileage.
 
I understand there will be a program to run the engine occasionally, so even if you never drive past battery range you'll go through a tank a year.
#409 of 544
Re: 50 MPG Possible after battery depletion? [tpe] by kdhspyder
Oct 02, 2008 (4:55 am)
Reply

Replying to: tpe (Sep 29, 2008 5:41 am)

I'm going to guess that the ICE is tuned to the Atkinson cycle since it's been stated that the ICE will run at a constant state in it's most efficient condition. I can see that a smallish 1.4L engine could run be tuned to run 1500-1800 rpms all the time with shutoff when there was little or no load.
 
That's essentially what the Prius 1.5L rates on the highway under the old EPA testing cycle. That's also what most drivers get in real life if conditions are perfect and speed is not too high.
 
50 mpg is very attainable with a combination of ICE and battery for an extended period....the current Prius is driving proof.
 
Essentially what GM has is a vehicle that will be equivalent to the Gen 3 Prius and prolly the new Insight for extended trips with no recharging. However it will also have the flexibility to be a gas-free vehicle for times around home ( or a recharging infrastructure ) where trips are short.
#410 of 544
Re: [stephen987] by reddroverr
Oct 02, 2008 (9:04 am)
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Replying to: stephen987 (Oct 02, 2008 3:19 am)

Referring to the VW in the artilce vs the Volt.
 
the vw engine would run after reaching 30 mph while the volt only kicks in after 40 miles driven. Therefore, the VW engine would run daily, while for a lot of people (me) the volt engine would run only a fraction of use days.
 
my current car isn't a Volt.
#411 of 544
Re: [reddroverr] by peralta
Oct 02, 2008 (9:48 am)
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Replying to: reddroverr (Oct 02, 2008 9:04 am)

"the vw engine would run after reaching 30 mph while the volt only kicks in after 40 miles driven. Therefore, the VW engine would run daily, while for a lot of people (me) the volt engine would run only a fraction of use days."
 
Not necessarily, if you look at other articles of golf twin drive, it has 82 hp electric motor that can move the car at highway speeds. If the trip is more than 30 miles, the ICE steps in around 30 mph (within the optimum efficiency range of ICE) to mazimize range.
 
However, it is ideal to use all the battery juice before the next recharge to the grid where the energy source is cheapest. That is why the integrated navigation comes into play to calculate to deplete the battery just in time for next recharge.
 
With battery depleted and the ICE being the sole motive force, the VW will likely beat the Volt in fuel efficinecy by a significant margin.
 
However, a current prius with Hymotion add-on lithium battery which is already in the market can run on pure EV up to 30 miles range of up to 52 mph. A more aggressive right foot will quickly summon the ICE for additional power. This thing is already in the market and a number of people (actual owners, not R&D staff) are driving them.

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